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### Course: 4th grade > Unit 11

Lesson 3: Parallel and perpendicular# Parallel and perpendicular lines review

Review the basics of parallel and perpendicular lines. Identify and draw parallel and perpendicular lines in some practice problems.

## What are ${\text{perpendicular lines}}$ and ${\text{parallel lines}}$ ?

*Want to learn more about parallel and perpendicular lines? Check out this video.*

## Practice set 1: Identify parallel and perpendicular lines

*Want to try more problems like this? Check out this exercise.*

## Practice set 2: Draw parallel and perpendicular lines

*Want to try more problems like this? Check out this exercise.*

## Want to join the conversation?

- Quick question how do you prove that lines are parallel? I can't seem to find that on here and i really need to know!(206 votes)
- If you draw a line through the 2 lines, it should be perpendicular to both lines.(44 votes)

- I am having trouble remember these. Anyone have any tips to help me remember?

Edit : Case Closed. But thank you Taylyn for answering my question! Everyone have a nice day.(46 votes)- Yes. In the word Parallel, the double L's are side by side, and if going on in a straight line, would never touch. So, the double L's in Parallel are, well, parallel. Use those as an example to help you remember what parallel means.(67 votes)

- Are perpendicular any kind of lines that intersect each other? I've got to know this!(26 votes)
- Yes, perpendicular lines intersect each other with 4 90-degree angles.(7 votes)

- Does a perpendicular line ALWAYS have to be 90 degrees? Just a Question(18 votes)
- Yes, a perpendicular line must always be at a 90-degree angle(32 votes)

- Why does the human brain have to know what geometry is?(13 votes)
- So it can identify shapes and measure things. It also helps make the human brain grow.

Hope this helps :D(20 votes)

- What happens if a Parallel line goes through a regular line so that make it perpendicular so what is that.(16 votes)
- If the parallel line goes through the line, the lines will not be parallel anymore, so they will only be perpendicular if they meet at a right angle.(13 votes)

- does perpendicular line have to be the exactly 90 degrees?(11 votes)
- It always have to be exactly at a right angle, and a right angle is always 90 degrees so yes.(6 votes)

- Parallel Lines is two lines thats are the same lines together. (Cant make a picture of it but you can look it up) Notice there's two lines that are crossed? That's Perpendicular! Perpendicular Lines are two Lines that do cross(11 votes)
- what is are perpendicular and parallel lines(5 votes)
- Perpendicular means they make a right angle. (A 45 degree angle) Parallel means they will go on forever and never meet.(7 votes)

- How to know if two lines are perpendicular if there are also lines that are connected and they aren't perpendicular?(5 votes)
- No it has to be a perfect 90 degree angle(1 vote)